How to write a Setup

As generically written physics analysis need additional information about a beamtime, such information is handled in Ant as so-called Setups. These Setups are kept in ant/src/expconfig/setups/. They implement the ant::expconfig::Setup_traits interface and are kept within a SetupRegistry using the AUTO_REGISTER_SETUP macro for easy access at run-time. The singleton class ExpConfig::Setup provides access to this registry, and the method ExpConfig::Setup::Get returns the currently selected setup. Each setup serves the following needs for reconstruction and analysis of events:

• Specify detectors the experimental setup consists of, in particular detectors. Reconstruct for example fetches clustering information from that, or physics classes can ask for the number of channels of specific detectors (if it's present at all).
• Specify calibrations, which turn the raw data into useful information for physics classes
  • Basic time and energy calibrations typically use a ant::Calibration::Converter to decode the notorious MultiHit CATCH TDCs, for example.
• Get general information about the beamtime, such as reasonable timing windows for prompt-random subtraction
• Set a start and end date of the beamtime via SetTimeRange(string start, string end) in the form "YYYY-MM-DD", this provides auto-detection of Setups for given input files via ExpConfig::Setup::SetByTID

Most of the basic functionality is already implemented in ant::expconfig::Setup, which provides in addition:

• Tell unpackers how to treat raw data by implementing the interfaces such as ant::unpacker::UnpackerAcquConfig using a list of detectors and asking them for the relevant information. Still, the setup can tweak this, see the BuildMappings method.
• Provide basic methods to keep detectors and calibrations (and in general Reconstruct hooks).